So-called cleavable surfactants have been known for several years and the different classes of such surfactants have been nicely reviewed by Stjerndahl et al. in Cleavable Surfactants, Novel Surfactants—Preparation, Applications, and Biodegradability, 2 ed., Holmberg ed., Marcel Dekker, Inc., USA, 2003. A main reason for the development of cleavable surfactants has been environmental concern and a desire for biodegradable surfactants. The main types of cleavable surfactants known today are:                1) Surfactants labile at acidic conditions        2) Surfactants labile at alkaline conditions        3) Light sensitive surfactants        4) Surfactants that degrade in contact with specific chemicals        5) Thermolabile surfactants        
According to Stjerndahl, most cleavable surfactants contain a hydrolysable bond and thus belong to type 1 or 2. For these surfactants, a change of pH is needed to initiate cleaving of the surfactant. The degradation product is often a soap or a long-chain alcohol, of which at least the former is clearly surface active. Thus, the cleaving of these compounds does not automatically imply that surface activity is lost.
In the case of light sensitive surfactants (type 3), the surfactant has to be exposed to light for a certain amount of time to obtain the desired cleaving.
Surfactants that decompose in contact with specific chemicals (type 4), e.g. ozone cleavable surfactants, are used in specific applications only.
For the group of known thermolabile surfactants (type 5), the decomposition rate is intended to be controlled by regulation of the temperature.
Hayashi et al. (JAOCS, Vol. 62, no. 3 (March 1985), 555–557) report preparation of amine oxide surfactants by oxidation of 2-alkoxy-N,N-dimethylethylamines with hydrogen peroxide. The 2-alkoxy-N,N-dimethylethylamine N-oxide surfactants formed were good foam stabilizers and stable up to 100° C., but decomposed rapidly to vinyl ethers at 150° C. Hence, the decomposition temperature of these surfactants is not compatible with use in aqueous compositions.
GB 923,449 discloses that unsaturated polymerisable compounds can be advantageously polymerised in aqueous medium and in the presence of dispersing agents and activators by using as a dispersing agent a salt of a partial ester of an aliphatic polycarboxylic acid with one or more alcohols having 3 to 20 carbon atoms and heating the resultant polymer emulsion at temperatures between 60 and 200° C. However, these dispersing agents have the drawback of being intrinsically sensitive to alkaline and acidic conditions, causing premature degradation of the surfactant under such conditions.
Conclusively, existing cleavable surfactants and dispersing agents of types 1–4 are either adapted for speciality applications only (being light sensitive or dependent on a specific substance) or cannot be utilised and cleaved at substantially constant pH conditions. Furthermore, cleaving does not always result in loss of surface activity. Existing thermolabile surfactants (type 5) are not suitable in water based applications and/or under alkaline or acidic conditions.